Dossier syncs emails from both internal employees and external senders to Asana. When you sign up for Dossier, emails between you and other employees at your company are published to Asana as private.
Employee emails are from senders with the same email domain as you and your colleagues. Ex. if you work at Trek Wheels, employees will have email addresses like email@example.com, or firstname.lastname@example.org. Emails between these employees are private and are securely published to Asana.
If team members have Asana user accounts, they are added as followers to the Asana task when they are cc’d on the incoming email. This maintains email privacy, so emails in Asana are only visible to team members who are on the conversation.
If recipients on the incoming email do not use Asana, then they are invisibly added to the Asana task, and will only receive an email from you when you reply to the emails in Asana.
You can reply to (using the #reply command), assign and even close the emails from the task, without ever leaving Asana. Any email replies also sync back to Asana as comments on the task. See help article Replying to emails from Asana.
To turn off syncing employee emails to Asana, login to Dossier, click Profile > My Account > Apps > Asana and uncheck the Sync team emails to Asana setting.